1. Field of the Invention
The present invention relates to a technology for making a determination on a collision of objects in a virtual space displayed as a two-dimensional image.
2. Description of the Background Art
There are technologies for making a determination on a collision of three-dimensional objects in a virtual three-dimensional space. According to such technologies, the three-dimensional objects are approximated to spherical or other cubic shapes, and it is determined whether the three-dimensional objects have collided against each other or not based on whether the approximate cubic (for example, spherical) shapes overlap or not. Such technologies can reduce the amount of calculations required for a collision determination as compared to a method of using shapes accurately reflecting the objects.
Japanese Laid-Open Patent Publication No. 10-165648 describes a technology of approximating objects to an elliptic spherical surface body. Japanese Laid-Open Patent Publication No. 7-152807 describes a technology of approximating objects to a spherical shape to perform rough checking and then approximating objects which have a possibility of interfering with each other to at least one fundamental cubic shape to perform precise checking. Japanese Laid-Open Patent Publication No. 7-230559 describes a technology of approximating objects to a great number of different spherical shapes.
The technology described in Japanese Laid-Open Patent Publication No. 10-165648 occasionally makes a determination on a collision more precisely than the technology of approximating the objects to a simple spherical shape, but often cannot make an appropriate determination on a collision due to certain conditions. The technology described in Japanese Laid-Open Patent Publication No. 7-152807 requires precise checking in addition to rough checking, which increases the amount of calculations. The technology described in Japanese Laid-Open Patent Publication No. 7-230559 requires a determination on a collision to be made on a great number of different spherical shapes for one object, which increases the amount of calculations.